Oil extraction



July 27, 1943.

F. B. LACHLE OIL EXTRAGTION Filed June 18, 1940 ATTORNEY Patented July27, 1943 OIL EXTRACTION Frank B. Lachle, San Mateo, Calif., assigner toThe Schwarz Engineering Company, Inc., San Francisco, Calif., acorporation of Nevada Application June 18, 1940, Serial No. 341,175

Claims.

This invention relates to the field of oil extraction, and is concernedmore particularly with the provision of a new oil extracting process ofwide application which enables improved results both quantitatively andqualitatively with vegetable and animal oils.

It is a general object of the invention to provide a new process ofextracting oil from oilbearing materials, such as vegetable and animalmatter.

Another object of the invention is to provide a process of the characterreferred to which is of a exible nature so as to be readily adapted andmodified for extracting oil from a wide variety of oil bearing materialsin an eicient manner which provides improved results both in thequantity and quality of the extracted oil.

Another object of the invention is to provide a novel oil extractingprocess which aords an approach to absolute oil recovery in that the oilcan be liberated from Virtually all of the oil cells.

Another object of the invention is to provide an oil extraction processin which the crude oil obtained in some applications of the process isof an unusually pure character so as to approximate refined oil incertain respects and therefore be capable of use in certain fieldswithout further treatment.

Another object of the invention is to provide an oil extraction processin which the material can be treated at a selected one of a wide rangeof temperatures in accordance with the particular characteristics of theproduct being treated and the attributes desired in the oil produced.

Another object of the invention is to provide a process for extractingoil from materials such as corn germs, wheat germs, cotton seed,peanuts, and other similar materials.

Another object oi the invention is to provide an oil extraction processwhich can be employed with eshy fruits and nuts, such as olives,avocados, and coconuts.

Another object of the invention is to provide an oil extraction processwhich can be employed in extracting oil from fish, such as sardines, andother animal matter with or without subjecting the material to heat.

Another object of the invention is to provide an oil extraction processwhich is economical and can be carried out with relatively inexpensiveequipment.

Other objects and advantages of the invention will be apparent from thefollowing description of certain preferred forms of the process asemployed with particular types of oil bearing materials.

In the drawing:

Figure 1 is a flow diagram of a complete oil extraction and recoveryprocess carrying out my invention.

Figure 2 is a fragmentary flow diagram illustrating the process asemployed with corn. germ.

Figure 3 is a fragmentary ow diagram illustrating the process asemployed with fish, such as' sardines.

Figure 4 is a fragmentary flow diagram illustrating the process asemployed with castor beans.

Figure 5 is a fragmentary ow diagram illustrating the process asemployed with coconut.

Figure 6 is a fragmentary ow diagram illustrating a modified process forrecovering the oil which has been liberated in the slurry.

The present invention,` as explained above, provides an oil extractionprocess of a new and novel character and as distinguished from priormethods which may be classified generally as mass pressure extractionmethods, solvent extraction methods,`and heat rendering methods. Knownmethods by their own limitations preclude the practical recovery of thegreatest percentage of oil possible from certain oil bearing materialsbecause they do not provide for the individual treatment of eachoil-bearing cell to eiect liberation of the oil.

In contrast to known methods, the process of the instant inventioncontemplates the dispersion of the material in a liquid medium so thatthe individual cells are separated to provide for wetting of each cellby the medium as it is separated and to provide for individual treatmentof each cell whereby it is crushed or ruptured to have the oil displacedtherefrom, or whereby the oil is expelled or expressed through thenatural pores of the cells. To effect this result, point pressure isapplied to each of the individual oil cells or oil cell groups in thepresence of a non-oil-soluble oil-carrying medium, such as water or anaqueous solution. The result preferably is obtained by providing atreating zone filled or partly filled with a displacing medium in whicha multiude of point pressure elTects are provided repeatedly andsuccessively so that after a period of treatment the mass of material isdelaminated to free the individual cells or cell groups and -eachindividual oil cell is free for separate treatment. The point pressurereferred to is that provided by surfaces having multitudinous minuteasperlties of such dimensions as to allow the asperin character. Withthis type ities to practically or actually touch or rub each other sothat the oil cell is pressed. cut, broken, squeezed or crushed betweenpressure surfaces having dimensions in the order of, or less than, theoil cell dimensions. Various surfaces providing a satisfactory type ofasperity are referred'td hereinafter. The point pressure effect iscontinued for a period of time sufficient to eliminate, or substantiallyeliminate the oil cell groups and provide a slurry or puree containingindividual oil cells and the oil-displacing medium. The same pointpressure effect used for delamination is also used to rupture ormacerate the oil cells to liberate the oil and allow it to be carriedaway by the oil-carrying medium or to eilect displacement of the oilthrough the pores of the cells by the application of pressure to theindividual cell.

In this Way. Substantially all of the oil-bearing cells can be treated,and the percentage. of oil recovery from various substances can bematerially increased. At the same time the process lends itself to thedirect production of a crude oil having certain or substantially all ofthe characteristics of refined oil. In many instances, the crude oilrecovered in accordance with this invention needs only certain finishingsteps, such as deodorization or clarincation, to compare favorably withrefined oils which are treated by known processes.

Generally it is, desirable that the oil bearing vegetables have asuillcient moisture content to activate the oil plasma which is believedto cause coalescence of the oil by virtue of the hydrophobic characterof the oil plasma. With some vegetables this is the natural state of theoil plasma in the ripe condition, while with others the activation mustbe effected by the imbibition of a suitable activating medium, such aswater. For example, usually the vegetables and nuts of the fleshy typesuch as olives, avocados and coconut contain a sufficient amount ofmoisture content when ripe and Vbefore dehydration to require noimbibition step. Other vegetable materials do not have a sufficientamount of moisture so that they require an imbibition step to properlycondition the oil plasma for the extraction step. i

In materials where an imbibition step is required,

the oil is believed to exist in the form of an oil plasma wherein theoil is distributed throughout the oil cells in very small particle size,some of which may be ultra-microscopic. The oil plasma is believedlgenerally to be in the form of a fine oil emulsion which is hydrophobicof materials, it is desirable to precede the actual extraction step witha period of imbibition wherein'the material is permitted to pick upmoisture. This imbibition step may be performed by applying anonoil-soluble liquid as generally classified, for example, by soakingthe material in water or by application of steam. or both, to conditionthe oil plasma for the extraction operation by causing coalescence oftheoil into droplets of a size to permit separation.

The imbibition is preferably effected with the material in its wholestate, although with some materials it may be desirable to effectimbibition during or after a comminution step where comminution of thematerial is desirable.

With certain of the materials, for example materials like corn germs, itis desirable to perform a starch reduction step either after orsimultaneously with the imbibition step. In the reducing step thematerial is subjected to the action of a suitable weak acid, such assulphuric acid or hydrochloric acid, to reduce the starch content tosugar, so that it will be dissolved from the kernel and will not be ableto act as an emulsifying agent. 'I'he dissolving of the starch from thekernel also serves to expose the germ itself for subsequent treatment.Preferably the reduction step would -be carried out with the material ina whole state, although it may be carried out by effecting either a wetor dry comminution of the material followed by application of the acid.

In some materials the imbibition and reduction steps should be effectedsuccessively, so that the imbibition step will serve to condition thematerial for the reduction step. In this way the reduction step may beperformed' more rapidly or with weaker acid to reduce. the possibilityof injury to the oil from the acid used in the reduction step anddecrease the expense of operation.

After the pre-treatment is completed, where required. the oil-bearingmaterial is placed in a treating chamber which contains a non-oilsolubleoil-carrying medium, such as water, and means for rst delaminating ordisintegrating the material to individual -cells or cell groups toprovide a dispersion of the individual cells or cell groups in themedium and then for treating the cells individually or while in a layerof approximately cellular thickness. Both the delamination and .thesubsequent pressure treatment of the cells is preferably eiiected bymeans of a multitudinous point pressure effect. Throughout the reductionand treatment, the non-oilsoluble oil-carrying medium should be presentin at least sufficient quantity to wet all of the solids of theoil-bearing material in all portions of the treating chamber and not inexcess of the amount required for eillcient operation. The desiredamount of medium provides a complete dispersion voi! the oil-bearingmaterial in the medium so that the individual cells or cell groupscomposed of two or more `cells are completely surrounded and wetted bythe medium. After the treatment is finished the oil-solids-water slurryor puree is usually of the consistency of cream.

With certain materials, it may be desirable to perform a comminutingstep of either a fine or coarse nature or both prior to the reduction ofthe material into cellular or small, multi-cellular particles.

Generally, it may be stated that the treatment of the material incellular or small multi-cellular particles in a dispersed form in anon-oil-soluble oil-carrying medium is of a character to extract some ofthe oil by actual rupturing or breaking of the cells to liberate .theoil in the medium; some of the oil may be displaced by osmosis; andother portions of the oil will be liberated .by complete or partialcollapse of the cell walls without rupture. The combined effect of thevarious types of extraction is lto recover a high percentage of the oilpresent in the material.

'I'he liberation of oil from the individual cells as explained may becarried out at cold` temperatures, i. e. temperatures in theneighborhood of ordinary room temperature (60 F.) or lower, where thisis desirable to provide a high quality oil, otherwise highertemperatures tend to hasten the process. Also, the oil liberation ispreferably effected in an acid mixture -to minimize the formation ofemulsifying agents such as soap. However. extraction may be performed inan alkaline medium.

The means for providing a multitudinous point pressure effect in thetreating chamber may take .the form of usual surfaces available, such asmetal or porcelain, which have a character of minute roughness (eventhough they may be apparently smooth) to approximate cellulardimensions. Preferably, the pressure surfaces are provided on aplurality of small pressure elements such as balls, pebbles, rods,discs, cubes, rolls, or plates and the like, which are loosely conned ina. treating chamber and subjected to agitation or vibration so as torepeatedly contact each other. This type of action is provided, forexample, by the cascading and sliding action of the pressure elementssuch as found in a ball mill of conventional design. For certainapplications, other equipment for producing individual pressuretreatment of the cells, such as a hammer mill or a colloid mill may beemployed.

In performing the extraction step with a ball mill, the oil carrying anddisplacing medium such as slightly acidic water is preferably addedfirst in order to minimize oxidation, and .the water may be pre-treatedif desired to liberate dissolved air. Subsequently, the oil-bearingmaterial is introduced into the ball mill winch is then placed inoperation for the requisite period of time which varies with diierentmaterials in accordance with the natural characteristics thereof.

The ball mill treatment may be carried at any selected one of a range oftemperatures depending upon the effect heating has on the quality of theoil and the eiciency ofthe ball mill operation. Usually heat isdesirable Where it can be employed to aid maceration of the cell wall.

After the required ball mill treatment, the mixture of solid material,water, water solubles, and

oil is flushed from the ball mill and subjected to subsequent treatmentto recover the oil or any other desired constituents. Various knownmethods of treatment may be used to recover desired constituents fromthe slurry.

One form of treatment which may be employed is that of centrifugalseparation which is preferably effected in two stages. The rst stage maybe effected with a common type of basket centrifuge to separate oil andWater from the remaining materials in the slurry. The second stage mayemploy a liquid separator centrifuge for separating the oil and thewater to recover cloudy Wet oil. The recovered oil may be dried as, forexample, in a continuous vacuum dryer and then filtered and placed instorage.

The above description is typical of extraction methods applicable tosubstantially all types of vegetable and animal materials which containoil in cellular form. The application of the process to certain of thespecific materials will now be described in detail.

Referring to Figure 1, a typical flow diagram is illustrated for use inthe recovery of olive or avocado oils.

Olives, for example, may be fed as indicated by the line Ill to acleaner where all stems, leaves, and material of similar character areremoved and where the olives may be washed if desired. The clean olivesare carried from the cleaner as indicated by the line I I to a pitter ofany desired construction Where the olive pits are removed.

It is preferred, however, to employ a ball mill pitter wherein the shellof the mill is perforated or formed by a screen and Where the pressureelements are of a character such as Danish pebbles, the ball load andthe speed of rotation being controlled so that the pulp or oilcontaining material is separated from both the pits and the skins whichare retained in the ball mill while the oil containing pulp isdischarged through the where required, is of '3 perforations. From thepitter, the pitted olives may be fed as indicated by the solid line I2to a conventional form of peeler where the skins are removed. From thepeeler, the peeled olives are discharged as indicated by the line I3 tothe ball mill. As indicated by the dotted line I4, both the pitter andthe peeler may be by-passed and the cleaned olives discharged directlyinto the ball mill or, as indicated by the dotted line I5, the pittedolives may be by-passed around the peeler and fed directly to the ballmill. Where the whole olives are fed directly to the ball mill, the ballload may be controlled so that the skins and the pits are no ground upduring the delamination of the oil cells. In this way, the pits andskins will not interfere with the oil extraction from the oil bearingcells.

Ordinary olives contain a suiiicient water content to serve as thenon-oil-soluble oil-carrying medium. Where olives have become partiallydehydrated, additional water may be required. In thisevent, a suitableamount of a non-oil-soluble oil-carrying medium, such as water, has beenplaced in the mill. The ball mill treatment may be continued foravpericd of, say, about fifteen to thirty minutes or for a suiiicientperiod to delaminate the olives and form a heavy slurry in which theolive is present in substantially cellular form in the non-oil-solubleoil-carrying medium. At the same time, the point pressure effect carriesout an individual treatment of each oil cell to liberate the oil. Thewater in the ball mill,

an amount to provide complete dispersion and wetting of the individualoil cells Without obtaining so great a dispersion as to interfere withthe eliiciency of the ball mill operation. Wher required, an amount ofwater will be added to the olives to provide a consistency of the slurrysimilar to that of cream. Microscopic examination of the slurry afterthe ball mill treatment has disclosed that substantially all of the oilcells have been separated and that there are few, if any, multicellulargroups of oil cells.

After the ball mill treatment, the entire constituents of the slurryincluding solids, water, Water-solubles and oil, are discharged asindicated by the line I6 into a basket centrifuge which serves toseparate the solids from the water and oil. The solids from the basketcentrifuge may be fed as indicated by the line Il to the solids dryer,while the mixture of oil and water, as indicated by the line I8, iscarried to a liquid separator centrifuge where the oil is separated fromthe water. The Water containing the water solubles may be fed from thecentrifuge, as indicated by the line I9, back to the liquid concentratorwhere it may be concentrated suiiiciently for drying, and fed, asindicated by the line 2D, to the solids dryer. 'I'he dried solids may becarried away as indicated by the line 2| to any suitable point ofdisposal.

The oil from the liquid separator centrifuge is still Wet and may beconveyed as indicated by the solid line 23 to a vacuumdryer. 'I'he drycloudy oil from the vacuum dryer is fed as indicated by the/line 25 to afilter press if suitable construction from which the dry brilliant oilis conveyed as indicated by the line 26 to a suitable place of oilstorage.

The press cake from the filter press may be carried as indicated by theline 21 to a press cake washer to liberate additional wet oil containedin the press cake, which may be carried from the press cake washer asindicated by the line 28 back to the vacuum dryer for further treatment.The oil-free cake from the press cake washer may be carried to asuitable point of disposal as indicated by the line 29. a

In a typical run carried out at room temperature in accordance with theprocedure outlined above, a 97% extraction by weight of oil has beenobtained from olives. After the extraction process as described, theolive oil is ready for use.

The recovery of avocado oil is substantially similar to that describedabove for olives except that it is desirable, although not neceary, tohave the material heated during the ba11 mill treatment. With avocadothis heating serves to materially hasten and facilitate the oil recoveryby softening the walls of the oil cells ,and by decreasing the viscosityof the oil. Usually the eiiiciency of the ball mill operation increaseswith a rise in temperature. However. the temperature employed for thetreatment should not be high enough to have a deleterious eiiect uponthe oil. If desired, the avocados can be controlled to remove the skinas a preliminary treatment in a ball mill operation as explained inconnection with olives to thereby obtain a higher quality oil.

Figure 2 illustrates a typical iiow diagram for a com germ oilextraction plant through the ball mill treatment. Whole corn germ may befed as indicated by the line 3l to the cleaner which serves to removethe husky material such as the corn germ caps and other undesirablesolid material. The cleaned whole corn germ may be fed as indicated byline 32 to an imbiber, which may comprise a tank having suitable meansfor the introduction of water, steam, or both, so that the whole corngerm can be treated for the requisite time to effect imbibition ofmoisture.

AS pointed out, the imbibition of moisture conditions the oil plasma ofthe corn germ for the extraction operation. The mbibed moisture isbelieved to activate the oil plasma because of its hydrophobic characterand is believed to reduce the viscosity of the oil plasma and overcomethe forces in the oil plasma which oppose coalescence of the oil. Thusthe oil tends to collect in minute droplets during the imbib-ition stepso as to be more readily available for further coalescence during theball mil1 treatment.

From the imbiber, the corn germs are fed as indicated by the line 33 toa digester wherein the l corn germs are subjected to the action of heatand a suitable starch reducing agent, such as Weak sulphuric orhydrochloric acid, or starch reducing enzymes. As indicated by thedotted line 34, the imbiber may be by-passed and the imbibition stepperformed at the same time as the starch reduction step in the digester.

During the starch reduction step, the acid reduces the starch to sugarswhich may be conveyed for disposal as indicated by the line 35 to asugar house for example. Duuing the reduction step, all or substantiallyall of the water solubles Will also be removed from around the corngerm. The reduction step therefore serves to expose the corn germ fordirect pressure treatment. Dui'- ing the digesting step, heat is alsopreferably applied, ior example by boiling, to speed up the reactionsandalso to aid in macerating the cell walls of the corn germ.

From the digester the starch-free corn germs may be carried as indicatedby the line 36 to the ball mill where they are subjected to themultitudinous point pressure effect in the presence of water. Usuallythe Water employed will be warmed and will have been deaerated. The

amount of water present is suilicient to produce the desired wetting anddispersion of the oil cells in the slurry, and the consistency of themixture at the end of the treatment will be similar to that of heavycream.

After the ball mill treatment, any suitable method may be employed forrecovering the oil, as for example, the steps indicated in Figure 1 withrespect to olives or avocados.

In a typical extraction run with the imbibing and digesting stepsperformed simultaneously, the cleaned whole corn germs were boiled forabout 20 minutes in a .3% solution of sulphuric acid. and then treatedin the ball mill with the additionof 300 to 400% water on a dry basisfor one and one-half hours. Subsequently the oil was recovered asdescribed in connection with Figure 1. A microscopic examination of thesolids residue showed that substantially all of the cells had given uptheir oil.

Figure 3 illustrates a process which may be employed for oil-bearinganimal materials, suchl as sardines, for example. The sardines may befed as indicated by the-line 4l to a cleaner where they may be washedthoroughly. Either whole sardines or the conventional form of sardinesfor canning may be employed. From the cleaner, the cleaned sardines arefed as indicated by the line 42 to a digestor where heat is applied, forexample in the form of steam, for softening and macerating the oil cellsand conditioning the fish for a ball mill operation.

t From the digestor thesoftened fish may be carried as indicated by theline 43 to the ball mill where they are subjected to the multitudinouspoint pressure effect in the presence of natural or added water asdescribed in connection with the preceding iiow diagrams. The ball milloperation may be suitably controlled to delaminate and disintegrate allmaterial except the bones, eyes and scales of the iish. The sh slurryfrom the ball mill may be treated to recover the oil as indicated inFigure 1. The oil recovered from sardines, for example, is of a yellowcolor and is considerably lighter in color, even where whole sardinesare used as the source, than the oil produced by conventional methods.In a typical run, whole sardines were boiled in water for about veminutes, and then treated in the ball mill for about one and one-halfhours.

Figure 4 shows a fragmentary flow diagram for use in recovery of oilfrom castor beans wherein the castor beans are rst cleaned and theneither passed directly, as indicated by the dotted line 46, to agrinder, or alternatively passed as indicated by the solid line 41 to apeeler to have the skins removed. The line 48 indicates feeding of thebeans tothe grinder where the beans are ground to facilitate the ballmill operation. If desired, the grinder may be by-passed as indicated bythe line 48a and fed directly from the cleaner to the ball mill.

From the grinder the groundbeans are fed through the line 49 to thehalf' mill where they are subjected to the multitudinous point pressureeffect in the presence of water to break up the oil cells and liberatethe oil as described in connection with other materials. If desired,heat may be applied during the ball mill treatment to accelerate theoperation by macerating the walls of the oil cells. In a typical ballmill treatment, about 100% of Water by weight was used,

, and the treatment continued for about one hour at a 'temperature ofabout 180 F.

After the ball mill treatment the oil may be recovered from theresulting slurry in any convenient manner. l

For the recovery of coconut oil, coconut meats may be fed as indicated`by the line to a digestor where they are subjected to heat, as forexample, by the use of steam or hot Water, after which they are fed asindicated by the line 52 to a peeler where the skins are removed. Ifdesired, either or both of the digestor and peeler may be by-passed andthe coconut meats fed directly to the grinder as indicated by the lines56 and 51.

From the peeler, the coconut meat is fed as indicated by the line 53 toacoarse grinder to effect a coarse comminuting operation, from which thecoarse ground meats are fed as indicated by the line 54 to a comminuterwhich elects a ne comminution of the material. From the comminuter thecomminuted meats are fed through the line 55 to a ball mill Where theyare subjected in the presence of say 200% Water by weight to the pointpressure eiect for a suiiicient time, say one hour, to reduce the meatto cellular form in the oil-carrying medium and to break the oil cellsand displace or express the oil therefrom. If desired, the finecomminuter 'may be by-passed as indicated by the line 58.

The slurry from the ball mill is then subjected to any suitable furthertreatment for recovery of the oil.

Figure 6 illustrates a modified process for recovering oil from theslurry resulting from the ball mill treatment. As shown, the slurry maybe conveyed from the ball mill by line lGa to a lter press from whichthe oil, water, and water solubles are carried by line l 8a to theliquid separator centrifuge. The press cake is then treated to removeany remaining oil by blowing with steam, water, or air, before beingdischarged through line 20a to the solids dryer.

I claim:

1. An oil extraction process for. cellular oilbearing materials whichincludes the step of reducing the material to .-substantially cellularform in an aqueous medium and liberating the oil from the individual oilcells by subjecting the material tothe action of cascading pressureelements in the presence of the medium.

2. An oilextraction process for cellular oilf bearing material whichincludes subjecting the material while in an added aqueous mediumto aball mill eifect for a period of time to reduce the material to cellularform for wetting by the medium and to apply pressure individually to thewetted oil cells to effect liberation of oil therefrom. r

3. An oil extraction process for cellular oilbearing material comprisingolives which includes the step of reducing the material to substantiallycellular form in an aqueous medium and liberating the oil from theindividual oil cells by subjecting the material to the action ofcascading pressure elements in the presence of the medium.

4. An oil extraction process for cellular oilbearing material comprisingsardines which includes the step of reducing the material tosubstantially cellular form in an aqueous medium and liberating the oilfrom the individual oil cells by subjecting the material to the actionof cascading pressure elements in the presence of the medium.

5. An oil extraction process for cellular oilbearing material comprisingcastor beans which includes the step of reducing the material tosubstantially cellular form in an aqueous medium and .liberating the oilfrom the individual oil cells by subjecting the material to the actionof cascading pressure elements in the presence of the medium.

FRANK B. LACHLE.

